JPS6393746A - Production of carboxylic acid - Google Patents

Abstract

PURPOSE:To safely obtain a carboxylic acid in high yield and purity at a low cost, by oxidatively cleaving olefins using hydrogen peroxide in the presence of a catalyst selected from tungstic acid, molybdic acid and heteropoly-acids thereof. CONSTITUTION:Olefins are oxidatively cleaved to produce a carboxylic acid useful as a raw material for esters, imides, amides, etc. In the process, the above-mentioned reaction is carried out by using hydrogen peroxide in the presence of one or more catalyst selected from tungstic acid, molybdic acid and heteropoly-acids thereof, preferably heteropoly-acid containing P or Si as a hetero atom, particularly H3PW12O40, H3SiW12O40, H3PMo12O40 and tungstic acid to safely afford the aimed compound in good yield and high purity at a low cost without using toxic metals with relatively ready separation of the product.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing carboxylic acids by oxidative cleavage of olefins.

[Prior art] Carphonic acids obtained by oxidative cleavage of unsaturated bonds in olefins, which are obtained in large quantities and at low cost from petroleum, animal and vegetable oils, are widely used as synthetic materials (such as esters, imides, amides, etc.). .

Various methods have been proposed to date for producing carboxylic acids by oxidative cleavage of olefins. For example, a method of oxidizing with a metal compound such as potassium permanganate, potassium dichromate, or ruthenium tetroxide, or a method of adding a catalytic amount of these compounds and using an oxidizing agent such as sodium hypochlorite or sodium periodate. (Bull, C.
henv, Soc, Jpn.

, 59.2637 (1986)), etc. are known.

Problems that the invention seeks to solve:However, these methods are not suitable for metals such as chromium yaruthenium, which are toxic, and sodium hypochlorite and sodium periodate, which are corrosive. Furthermore, it is expensive and therefore impractical. Furthermore, these oxidizing agents are unstable under acidic conditions and the reaction must be carried out under basic conditions. Therefore, a neutralization step is required, making the manufacturing process complicated and industrially disadvantageous. For these reasons, a method for producing carboxylic acids safely and inexpensively by oxidatively cleaving olefins under acidic conditions has been desired.

Hydrogen peroxide is a suitable oxidizing agent in the production of carboxylic acids because it is inexpensive, noncorrosive, and stable under acidic conditions. However, since this substance is water-soluble, when it acts on oil-soluble substances, special and expensive catalysts such as those made by introducing alkyl-substituted ammonium or phosphonium into tungstic acid or molybdic acid to make it oil-soluble are used. Only a method (JP-A-60-34921) is known, and a method using a water-soluble catalyst is not yet known.

In addition, when cations such as sodium, potassium, ammonium, phosphonium, etc. coexist in the reaction system as in the above method, the purity and yield of the produced carboxylic acid decreases, and a separate purification process is required. There's a problem. That is,
In order to easily and inexpensively produce carboxylic acids, the presence of any cation other than protons causes disadvantages in production.

However, according to research conducted by the present inventors, it was unexpectedly possible to use tungstic acid, which is not oil-soluble, as a catalyst without any of the above treatments, and to use hydrogen peroxide as an oxidizing agent to act on olefins. It has been revealed that by doing so, the double bond is oxidatively cleaved very effectively and the corresponding mono- and σ/or dicarboxylic acids are obtained. or,
It has been found that the double bonds of olefins are oxidatively cleaved when molybdic acid is used as a catalyst, similar to the above-mentioned tungstic acid.

Furthermore, the present inventors have found that when using a heteropolyacid such as tungstic acid or molybdic acid as a catalyst, the double bonds of olefins are efficiently oxidized and cleaved by hydrogen peroxide, and the corresponding mono- and/or dicarboxylic acid is It has been found that it can be produced with high yield and high purity.

The present invention was completed based on the above new findings.

That is, an object of the present invention is to provide a novel and useful catalyst for a method of producing carboxylic acid by oxidative cleavage of olefins with hydrogen peroxide.

[Means for Solving the Problems] The present invention provides for the production of carboxylic acids by oxidative cleavage of olefins using one or two selected from the group consisting of tungstic acid, molybdic acid, and their heteropolyacids. The gist of the invention is to perform oxidative cleavage with hydrogen peroxide in the presence of more than one type of catalyst.

Olefins in the present invention include aliphatic and alicyclic hydrocarbons having 4 to 8 carbon atoms such as butene, pentene, hexene, octene, cyclopentene, cyclohexene, cyclooctene, dicyclobentenol, sulfolene, holone, isophorone, Examples include olefins having functional groups such as carbonyl groups, hydroxyl groups, carboxyl groups, ester groups, and sulfonyl groups, such as oleic acid, palmitoleic acid, linoleic acid, lyluic acid, wasylic acid, and esters thereof. The above-mentioned functional group may be a group that is oxidized like olefins, as long as it does not inhibit the reaction according to the present invention, and may contribute to the progress of the reaction depending on the conditions.

Examples of the catalyst according to the present invention include tungstic acid, molybdic acid, and heteropolyacids thereof. The heteropolyacid referred to herein is a condensed acid consisting of two or more types of oxyacids, and the polyacid atoms include tungsten and molybdenum, and the heteroatoms include the following various types. The heteroatom C in the heteropolyacid of tungstic acid is P, AS, or Si.

Examples include Ti, Co, Fe, B, V, Be, lNi, Ga, and the like. Specific examples of heteropolyacids of tungstic acid are as follows: ), H5 [BW1204o], H3 [VW1204o], H6 (BeWg 031), H6 (TeW6024), H5 [IW6024], H4 (N! W602486), H3 (GaW6 o24”6), H6 (P2 W18062]・H (AS2W13062) and H7[PW11033].

In addition, the heteroatoms in the heteropolyacid of molybdic acid include P, AS, Si, Ge, Ti, Ce, Th, M
Examples include n5N i, Te, L Co5Cr, and Fe5Ga. Specific examples of heteropolyacids of molybdic acid include the following structural formulas: H3 (P M O12040), H3 (ASMO12040), H4 (SI M O12040), Machi (G e M O12040), H4 (T! M O12040), HB (08MO12042), HB (ThMO12042), H7 (PM01103.), H7 (ASM01103g), HB (G e M 01103g), H6 (MnMO
9032), H6 (N! M O9032), H6 (TeMOs024), H5 (IMo6024), H3 (COM Os 024H6), H3 (Cr M O6024H6), H3 (FeMOs o24”6), H3 (GaMO
6024H6), H4(N t Mo6 o24”B ), H6(P 2
Examples include those having M013062) and H6 (AS2 MOH3062).

Furthermore, mixed coordination heteropolyacids in which two or more of each type of atoms are coordinated, such as H4P M OW 11040°H4PReW1104o1 H4P VM O11040°H5P V 2 M O100401 H3PMO6W6040, can also be used. All of these heteropolyacids exemplified above are known. From the viewpoint of ease of synthesis or availability, heteropolyacids containing P or Si as a heteroatom are preferred, particularly 12-tungstophosphoric acid (H3PW1204o), 12-tungstophosphoric acid (H3PW1204o),
-TungstoKi M (H3S i W18O49),
12-molybdophosphoric acid (H3PMO12040) and the like are more preferred.

Further, the tungstic acid, molybdic acid, or a heteropolyacid thereof used as the catalyst may be a hydrate, and furthermore, the tungstic acid, molybdic acid, or a heteropolyacid thereof may be produced in the reaction system. It may be in the form of a 1q compound. Such compounds include MC3
, MC16 and MS3 (M=W or MO), oxides, chlorides and sulfides are exemplified.

When such oxides, chlorides, and sulfides are used, it is preferable to add a mineral acid such as phosphoric acid, hydrochloric acid, or sulfuric acid to the reaction system and conduct the reaction under acidic conditions of DH4 or less. Also, the catalyst may be added in acid form and mineral acids may also be used.

The catalysts exemplified above may be used alone or in combination of two or more.

In terms of reactivity, heteropolyacids are preferred, and in terms of balance between reactivity and cost, tungstic acid is preferred.

The manufacturing method according to the present invention is generally carried out as follows. That is, olefins and a catalyst as raw materials are charged into a reactor, hydrogen peroxide is added, and the reaction is carried out in a solvent while being heated and stirred.

The concentration of olefins during the reaction is not particularly limited. However, when the reaction mixture is cooled after the reaction is completed and the resulting carboxylic acid is crystallized and isolated, the concentration of olefins should be approximately 2 to 70% by weight from the viewpoint of the amount and quality of crystals precipitated. The content is preferably 15 to 60% by weight, and more preferably 15 to 60% by weight.

The amount of catalyst to be used is selected from a wide range as long as it is an effective amount to exhibit catalytic activity. However, from the viewpoint of reaction rate and catalyst cost, in terms of free acid (tungstic acid, molybdic acid, or their heteropolyacids),
Advantageously, the amount is about 0.01 to 30% by weight, preferably about 1 to 10% by weight, based on the olefins.

The stoichiometric amount of hydrogen peroxide required for this reaction is 4 mol per 1 mol of olefins, but in reality it is 10 to 50 mol.
It is desirable to use % excess.

The concentration of hydrogen peroxide in the reaction mixture can be selected from a wide range. The lower limit is a concentration sufficient for the catalyst that has oxidized olefins to recover its oxidizing ability with hydrogen peroxide, and even if the catalyst is quite dilute, the oxidation reaction will proceed, although the reaction rate will inevitably decrease. Further, there is no particular upper limit, and the concentration may be quite high. However, from the viewpoint of improving the reaction rate and reducing production costs by using low concentration hydrogen peroxide, 0.1 mmol/l
- About 12 mol/l, preferably 10 mmol/l - 8
A value of the order of mol/l is advantageous. Hydrogen peroxide is usually supplied in the form of an aqueous solution.

Water is suitable as a reaction solvent. Water-miscible organic solvents, such as alcohols having 1 to 4 carbon atoms, and alcohols having 1 to 4 carbon atoms.
It is also possible to use the carboxylic acid No. 4, dioxane, tetrahydrofuran, dimethylformamide, etc. alone, or in combination with water within a range that maintains a homogeneous phase.

The reaction temperature is usually 20 to 100°C from the viewpoint of reaction rate.
However, when the reaction is carried out under pressure, a reaction temperature of up to about 150° C. can also be employed. From the viewpoint of reaction rate and prevention or suppression of decomposition of hydrogen peroxide, it is preferable to carry out the reaction at about 50 to 130°C.

The reaction time may vary depending on the concentration of olefins, catalyst and hydrogen peroxide, reaction temperature, etc., but is usually about 1 to 24 hours.

After the reaction is completed, the produced carboxylic acid can be separated from the reaction mixture by a method more suitable for each physical property.

For example, it may be distilled, or it may be topped with a reaction solvent and then recrystallized using any solvent.

In the method of slowly cooling a reaction mixture to crystallize a carboxylic acid, when a heteropolyacid, especially a heteropolyacid such as tungstic acid, is used as a catalyst, a clear reaction mixture can be obtained because these heteropolyacids dissolve well in water and other reaction solvents. When the reaction mixture is slowly cooled, the produced carboxylic acid precipitates as crystals, and can be very easily separated by filtration from the mother liquor in which the catalyst and unreacted olefins are dissolved. After separation, the mother liquor can be used for the reaction again, and no deactivation of the catalyst is observed. The isolated crystals are purified by drying as they are, or by washing with water and recrystallizing if necessary. On the other hand, when using tungstic acid or molybdic acid as a catalyst, the catalyst tends to precipitate when the hydrogen peroxide concentration in the reaction system decreases, and the precipitated catalyst mixes with the produced carboxylic acid, reducing the purity of the target product. invite. Therefore, when using tungstic acid or molybdic acid as a catalyst, it is necessary to maintain the hydrogen peroxide concentration at a level above which these catalysts remain in a dissolved state even in the isolation step after the completion of the reaction, or to remove the precipitated hydrogen peroxide immediately after the reaction. It is desirable to perform crystallization after separating the catalyst by filtration or the like.

By performing such an operation, the target carboxylic acid can be isolated with high purity and high yield equivalent to when using a heteropolyacid.

[Example] The present invention will be described in detail below with reference to Examples.

Example 1 Cyclohexene 16 in a glass 4-bottle flask with a stirrer
．． 89 (0.2 mol), 60% hydrogen peroxide solution 50 Ij
(0.88 mol), tungstic acid 0°749 was added,
The mixture was heated to reflux while stirring vigorously. Reflux temperature is 74
The temperature increased from °C to 100 °C over time. After 3 hours of reaction, the production rate of the corresponding carboxylic acid was calculated by gas chromatography internal standard method of the reaction solution, and was found to be 95 mol % of adipic acid and 3 mol % of glutaric acid. This reaction solution was cooled and crystallized to form adipic acid crystals at 24
．． 59 (yield 86 mol%) was obtained.

Example 2 Cyclopentene 13°69 in a glass autoclave
(0.2 mol) and 60% hydrogen peroxide solution 509.12-tungstophosphoric acid 29 hydrate 0.6 g were used, and the production rate of carboxylic acid was 90 mol% of glutaric acid and 2 mol% of succinic acid. Rarely. This reaction solution was topped with water and re-crystallized with benzene to form crystals of glutaric acid.
(yield: 88 mol%).

Example 3 Cyclohexene 16.89, ter
Charge 303 g of t-butanol and 5.0 g of molybdic acid, and while heating and refluxing, add 50 g of 60% hydrogen peroxide solution.
It dripped in time. Thereafter, the reaction was completed by rapid flow for 3 hours. When the reaction solution was measured by gas chromatography internal standard method, the production rate of the corresponding carboxylic acid was 186 mol % of adipine and 2 mol % of glutaric acid.

Example 4 A reaction was carried out in the same manner as in Example 1, except that 3°03 of 12-molybdoline w129 hydrate was used as a catalyst. As a result of measurement by gas chromatography internal standard method, the production rate of the corresponding carboxylic acids was 92 mol% for adipic acid and 5 mol% for glutaric acid.

Example 5 In the reactor of Example 1, 27.6 g (0.2 mol) of isophorone, 309.1 of water and 1.2-dungest silicic acid ditetrahydrate were added.
When 30% hydrogen peroxide solution 1409 was added dropwise over 3 hours while stirring at 80° C., intense foaming was observed. The reaction was continued for 8 hours until the bubbling stopped. When the reaction solution was measured by gas chromatography internal standard method, the production rate of 3,3-dimethylglutaric acid was 50 mol%. Isophorone could not be detected.

Example 6 Into the reactor of Example 1, 30 g of dicyclobentenol (0,
After charging 0.9 g of water 609.12-tungstophosphoric acid 29 hydrate (2 mol), 60% hydrogen peroxide solution 509 was added dropwise over 2 hours while stirring at 90°C, and the reaction was further carried out for 4 hours. . As a result of measuring this reaction solution by gas chromatography internal standard method, the production rate of the corresponding carboxylic acid was 58 mol %, which was rare. However, when the neutralization value of this solution was measured, 0.44 mol of carboxyl groups were generated by the reaction. was being generated. Therefore, when 60% hydrogen peroxide solution 509 and 0.9 g of catalyst were added and the reaction was continued for 10 hours,
Tricarboxylcyclopentyl acetic acid was obtained at a production rate of 60 mol% (based on gas chromatography internal standard method). At this time, the amount of carboxyl groups produced calculated from the neutralization value was 0.73 mol%.

Example 7 In the reactor of Example 1, industrial oleic acid (iodine number 90.
2> 1 barley prepared with 28 g, water 50 g, and 2.09 g of 12-tungstophosphoric acid 29 hydrate, and 579 g of 60% hydrogen peroxide solution was added dropwise over 5 hours while stirring vigorously at 90'C.
The reaction was carried out for 5 hours.

After topping the reaction solution with water, it was distilled under reduced pressure.
1 tsubo of monocarboxylic acid and dicarboxylic acid. As a result of calculating the production rate of the corresponding carboxylic acid to the unsaturated fatty acid contained in industrial oleic acid from the type of each fraction and gas chromatography, it was found that pelargonic acid was 64 mol%,
27 mol% of short chain monocarboxylic acids with 8 or less carbon atoms, 79 mol% of azelaic acid, 11 mol% of long chain dicarboxylic acids with 10 or more carbon atoms, 5 mol% of short chain dicarboxylic acids with 8 or less carbon atoms.
Met.

[Effects of the Invention] Since the production method according to the present invention uses hydrogen peroxide, carboxylic acid can be produced safely and inexpensively without using harmful metals. Furthermore, the yield of the obtained carboxylic acid is high, and the separation of the produced carboxylic acid is relatively easy, making it possible to obtain the target product with a high degree of MA.

Therefore, the production method according to the present invention is an industrially excellent method for producing carboxylic acids.

Claims (1)

[Claims] In producing carboxylic acids by oxidative cleavage of olefins, oxidative cleavage is performed with hydrogen peroxide in the presence of one or more catalysts selected from the group consisting of tungstic acid, molybdic acid, and their heteropolyacids. A method for producing carboxylic acid characterized by the following.